Merge pull request #1205 from kyuupichan/if-cleanup-final

Fix two races in interface.py.

lib/interface.py

@@ -17,16 +17,16 @@
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 
-import re, errno, os
+import copy, re, errno, os
 import threading, traceback, sys, time, Queue
 import socket
 import ssl
 
-import x509
-import util
 import requests
 ca_path = requests.certs.where()
 
+import util
+import x509
 from version import ELECTRUM_VERSION, PROTOCOL_VERSION
 from simple_config import SimpleConfig
 
@@ -40,8 +40,7 @@ def Interface(server, response_queue, config = None):
     - Member functions send_request(), stop(), is_connected()
     - Member variable server.
     
-    "is_connected()" is currently racy.  "server" is constant for the object's lifetime and hence
+    "server" is constant for the object's lifetime and hence synchronization is unnecessary.
-    synchronization is unnecessary.
     """
     host, port, protocol = server.split(':')
     if protocol in 'st':
@@ -55,7 +54,12 @@ class TcpInterface(threading.Thread):
         threading.Thread.__init__(self)
         self.daemon = True
         self.config = config if config is not None else SimpleConfig()
-        self.connected = False
+        # Set by stop(); no more data is exchanged and the thread exits after gracefully
+        # closing the socket
+        self.disconnect = False
+        # Initially True to avoid a race; set to False on failure to create a socket or when
+        # it is closed
+        self.connected = True
         self.debug = False # dump network messages. can be changed at runtime using the console
         self.message_id = 0
         self.response_queue = response_queue
@@ -250,7 +254,7 @@ class TcpInterface(threading.Thread):
     def send_request(self, request, response_queue = None):
         '''Queue a request.  Blocking only if called from other threads.'''
         self.request_time = time.time()
-        self.request_queue.put((request, response_queue), threading.current_thread() != self)
+        self.request_queue.put((copy.deepcopy(request), response_queue), threading.current_thread() != self)
 
     def send_requests(self):
         '''Sends all queued requests'''
@@ -271,14 +275,11 @@ class TcpInterface(threading.Thread):
             self.message_id += 1
 
     def is_connected(self):
-        return self.connected
+        return self.connected and not self.disconnect
 
     def stop(self):
-        if self.connected and self.protocol in 'st' and self.s:
+        self.disconnect = True
-            self.s.shutdown(socket.SHUT_RDWR)
+        self.print_error("disconnecting")
-            self.s.close()
-        self.connected = False
-        self.print_error("stopped")
 
     def maybe_ping(self):
         # ping the server with server.version
@@ -290,7 +291,7 @@ class TcpInterface(threading.Thread):
             self.print_error("interface timeout", len(self.unanswered_requests))
             self.stop()
 
-    def get_response(self):
+    def get_and_process_response(self):
         if self.is_connected():
             try:
                 response = self.pipe.get()
@@ -298,28 +299,30 @@ class TcpInterface(threading.Thread):
                 return
             # If remote side closed the socket, SocketPipe closes our socket and returns None
             if response is None:
-                self.connected = False
+                self.connected = False  # Don't re-close the socket
-            return response
+                self.print_error("connection closed remotely")
-
+            else:
-    def run(self):
-        self.s = self.get_socket()
-        if self.s:
-            self.pipe = util.SocketPipe(self.s)
-            self.s.settimeout(0.1)
-            self.connected = True
-            self.print_error("connected")
-
-        self.change_status()
-        if not self.connected:
-            return
-
-        while self.connected:
-            self.maybe_ping()
-            self.send_requests()
-            response = self.get_response()
-            if response:
                 self.process_response(response)
 
+    def run(self):
+        s = self.get_socket()
+        if s:
+            self.pipe = util.SocketPipe(s)
+            s.settimeout(0.1)
+            self.print_error("connected")
+            # Indicate to parent that we've connected
+            self.change_status()
+            while self.is_connected():
+                self.maybe_ping()
+                self.send_requests()
+                self.get_and_process_response()
+            if self.connected:  # Don't shutdown() a closed socket
+                s.shutdown(socket.SHUT_RDWR)
+                s.close()
+
+        # Also for the s is None case 
+        self.connected = False
+        # Indicate to parent that the connection is now down
         self.change_status()
 
     def change_status(self):